(s^4) (v^3) (x^7) is < 0.
S^4 will always be positive, irrespective of whether s is negative or positive.
So for the product to be negative either one of v^3 & x^7 has to be negative (and the other one positive). In other words either x or v has to be negative and the other one positive.

Consider (1) v < 0. This means x is positive. Since we do not know about s (1) is not sufficient.
Consider (2) x > 0. Again this only tells us that v should be negative. Same as (1). Since s is not known this is not sufficient.

I think the answer should be E.

I think OA is not correct.IMO ans is E

S^4V^3X^7<0
or (SX)^4 * (VX)^3 <0
now (SX)^4>0..so (VX)^3<0 or VX<0

so to know whather svx<0 we need to know the sign of s.None of the options provide that.Hence ans should be E

st 1:
s + or -
v -
x+

svx dependent on sign of s which can be + or -

st 2:

s+ or -
v-
x+

svx dependent on sign of s which can be + or -

both insufficient